[alsa-devel] [PATCH v2 1/3] ALSA: hda - add new function snd_hda_bus_reset() for codec communitation error

[mengdong.lin at intel.com]

From: Mengdong Lin <mengdong.lin at intel.com>

A new function snd_hda_bus_reset() is defined to reset all codecs on the bus.
This is implemented as temporary suspend-and-resume calls to codecs as an
ad hoc solution.

It will be called by bus reset ops azx_bus_reset() as a rescue of codec
communitation error, replacing calls to snd_hda_suspend and snd_hda_resume.

It's because snd_hda_resume need change for system resume: It will delay
resuming a codec that is not ready to resume for some external dependency, to
avoid blocking system resume. But this change of "delay resume" is not suitable
for recovering from codec communication error, which need resume the codec
immediately after suspend to simulate a bus reset.

Signed-off-by: Mengdong Lin <mengdong.lin at intel.com>

diff --git a/sound/pci/hda/hda_codec.c b/sound/pci/hda/hda_codec.c
index 17286b3..ba147d7 100644
--- a/sound/pci/hda/hda_codec.c
+++ b/sound/pci/hda/hda_codec.c
@@ -5523,6 +5523,29 @@ int snd_hda_resume(struct hda_bus *bus)
 	return 0;
 }
 EXPORT_SYMBOL_HDA(snd_hda_resume);
+
+/**
+ * snd_hda_bus_reset - reset the codecs on the bus.
+ * @bus: the HDA bus
+ *
+ * This is implemented as temporary suspend-and-resume calls
+ * to codecs as an ad hoc solution.
+ *
+ * Returns 0 if successful.
+ */
+int snd_hda_bus_reset(struct hda_bus *bus)
+{
+	struct hda_codec *codec;
+
+	list_for_each_entry(codec, &bus->codec_list, list) {
+		cancel_delayed_work_sync(&codec->jackpoll_work);
+		if (hda_codec_is_power_on(codec))
+			hda_call_codec_suspend(codec, false);
+		hda_call_codec_resume(codec);
+	}
+	return 0;
+}
+EXPORT_SYMBOL_HDA(snd_hda_bus_reset);
 #endif /* CONFIG_PM */
 
 /*
diff --git a/sound/pci/hda/hda_codec.h b/sound/pci/hda/hda_codec.h
index c93f902..6061360 100644
--- a/sound/pci/hda/hda_codec.h
+++ b/sound/pci/hda/hda_codec.h
@@ -1076,6 +1076,7 @@ void snd_hda_unlock_devices(struct hda_bus *bus);
 #ifdef CONFIG_PM
 int snd_hda_suspend(struct hda_bus *bus);
 int snd_hda_resume(struct hda_bus *bus);
+int snd_hda_bus_reset(struct hda_bus *bus);
 #endif
 
 static inline
diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c
index 735567e..6f11c7a 100644
--- a/sound/pci/hda/hda_intel.c
+++ b/sound/pci/hda/hda_intel.c
@@ -1659,8 +1659,7 @@ static void azx_bus_reset(struct hda_bus *bus)
 		struct azx_pcm *p;
 		list_for_each_entry(p, &chip->pcm_list, list)
 			snd_pcm_suspend_all(p->pcm);
-		snd_hda_suspend(chip->bus);
-		snd_hda_resume(chip->bus);
+		snd_hda_bus_reset(chip->bus);
 	}
 #endif
 	bus->in_reset = 0;
-- 
1.7.10.4